Coiling means for making elastic coil structures



July 2 94 4 R. J. AIQNOLD COILING FOR MAKING ELASTIC COLL STRUC'IURE Filed Aug. 25, 1944 Patented July 22, 1947 COILING MEANS FOR MAKING ELASTIC COIL STRUCTURES Ralph J. Arnold, Western Springs, Ill., assignor, by mesne assignments, to Kellogg Switchboard and Supply Company,

tion of Illinois, and

Beverly Hills, Calif.

Chicago, 111., a corporato Ralph D. Collins,

Application August 25, 1944, Serial No. 551,245

3 Claims. 1

This invention relates to means for making elastic coil structures and more particularly coiling means therefor.

It is now well known that retractile and extensible extension cords or cables, for various purposes, principally electrical, may be satisfactorily constructed by providing a conductor or a plurality of conductors with a covering or sheath of incompletely vulcanized rubber or the like, then closely coiling it into the form of a helix, and then vulcanizing it, after which the cable will be readily extensible, as, for example, for extension cord purposes, without damage thereto while being automatically retracted by its own resilience to closely coiled helical formation when released.

In application of Paul C. G'eraty, Serial No. 551,246, filed August 25, 1944, now Patent No. 2,394,762 improved methods and means are disclosed and claimed for the making of such cables, and the present application aims to provide further improved meanstherefor.

In application of Ralph D. Collins, Serial No. 577,111, filed February 9, 1945, improved methods and means are broadly disclosed for the making. of such cables with tangent ends, and the present application aims to provide further improved means therefor.

The invention will be understood by reference to the following description, taken together with the accompanying drawings, showing illustrative embodiments of the invention, and in which' Figure 1 is a view showing a rotatable mandrel with the cable coiled thereon for vulcanizing and showing improved means in accordance with the present invention for forming the cable;

Figure 2 is an enlarged view of a portion of the structure of Figure 1 but showing a free end of the cable in the process of being coiled;

Figure 3 is an enlarged view similar to Figure 2 but showing another portion of the structure of Figure 1, but also with a free end of the cable in the process of being coiled;

Figure 4 is an enlarged separated view of means employed in the making of the cables; and

Figure 5 shows a modified form of similar means. p

In the said Geraty and Collins applications, it is pointed out that two objects are desirable in the making of cables of this type, one being the economy of manufacture accomplished by producing individual coiled lengths of the cable in preliminarily interconnected relationship, thereafter to be severed into individual lengths, and

second to produce uncoiled connecting tails or tangents at each end of the final individual cables, and reference is desirably made to said Geraty and Collins applications for a description of the methods and means therein broadly described and claimed for accomplishing both of these objects, and as well as for a description of the preliminary uncoiled cable, with which the invention treats, and the final individual lengths of coiled cable in both compacted and extended form as when used say as an extension cord for any purpose.

In the practice of the present invention also the usual mandrel is employed, in the form here shown of an elongated metal rod Ill upon which is wound the cable II, which may enclose one or more and usually a plurality of conductors such as electric wires and the conductors being encased in a vulcanizable sheath or covering of rubber-like material which may be somewhat raw conventional rubber or may be one of the many synthetic elastomers which are now on the market, all as more particularly described in said Geraty application.

In accordance with the improvements of the present invention, however, and to begin the coiling of the cable I l on the rod [0 to provide an anchorage for the leading and trailing ends of the cable on the rod, as well as providing a hump in the cable at each end of each of the preliminarily interconnected individual cable lengths, improved means are here shown an embodiment of which, before being placed on the rod II], is best shown in Figure 4 of the present drawings.

As will be there seen, such means comprises a spring clip indicated generally by the numeral 12 and which may be conveniently formed of spring wire l3 bent to form an outer closed elongated loop I 4 as by having the otherwise free ends of the wire l3 soldered or brazed as at l5. One end of the loop M (in Figure 4, the lower end) is bent back in upon itself in a reentrant portion I 6 which is first decreasingly tapered inwardly and then slightly enlarged at its inner end to provide an open inner sprin loop H. In the present example, the inner loop I! is a continuation of a. portion of the spring wire l3 which is carried still further inwardly and is coiled as at l8 to provide a torsion spring effect upon the arms I9 of the inner spring loop IT. The torsion coil spring [8 thus formed is placed under enhanced tension when the arms [9 of the inner spring loop I 1 are spread apart, and thus the torsion coil spring [8 portion of the clip I2 tends to compress the inner loop l! for purposes next pointed out. The spring portion 18 also tends to stabilize the clip and prevent its losing shape under repeated usage.

The clip l2 may embody either round or flat stock metal and may be formed with the metal in a relatively soft state and then heat treated to give it the desired spring steel qualities, or it may be formed with the metal pre-hardened.

When it is desired to begin coiling of the cable I I on the rod ID, the clip 12 is placed on the rod as at A, somewhat in the manner of a clothespin, the rod passing up through the re-entrant portion [6 of the clip and being lodged in'the spring loop ll, the clip and rod being maintained in this relationship both by the spring eifect of the decreasingly tapered re-entrant portion l6 of the clip as well as enhanced by the torsion effect of the coil spring H! in the interior of the clip, the inner spring loop ll being placed under tension when the rod i is received therein.

Furthermore, at the start of the winding of the cable on the rod, the leading end 20 of the cable, as already alluded to, may be also anchored to the rod by being received together with the rod within the spring loop H, the loop yielding sufficiently both to receive the rod already under ten ion within the spring loop I! and the end 26 of'the cable, thus anchoring the latter in position for winding.

Next, the cable is run up over the end of the clip I2 opposite the end which has the reentrant portion [6 therein, and, at this other end, the clip is retuse as by being bowed in slightly as at 21 to provide a saddle for the cable passing therecver in the form of 'a hump, as at 22.

Next, the coiling ofthe cable on the rod IS in compacted helical form, as at 23 is continued during which the rod It] may be mechanically rotated by any suitable means. This coiling of the cable on the rod may be continued until any desired predetermined length is provided in coil form, and when suificient of the cable has been coiled'for the desired individual cable length, another of the clips 12 is placed upon the rod it as at B, the cable being passed over the end 2i of the clip to form another hump as at '24.

Again coiling of the cable on the rod is continued until another predetermined length has been provided and finally the third clip I2 is placed on the rod as at C. If, as here shown, this clip C is adjacent the trailing 'end of the cable, the cable is merely humped thereover as at 25 and the otherwise free endof'the cable 26 is clamped to' the rod in by the clip l2 just as the leading end 20 of the cable was so clamped.

It will be recognized that for economy of operation the rod or mandrel it must be rotated at considerable speed to avoid unnecessary slownessin the production of the coiled cable, and, at such speeds of rotation as are desirable for this purpose considerable centrifugal force is generated so that the clip ends 2| and the cable humps thereon have appreciable moments of inertia at saythe points 22, 24 and 25. These forces would tend to shake or vibrate the rod it, to an objectionable extent, if they were not balanced on a'diametrically opposite side of the rod it, and this is accomplished in thisinstance asby having the clip l0 extend transversely on opposite'side's of the axis ofthe rod, that is, the end of'the clip having the reentrant :portion i6 extendingto one side of the axis of the rod and the other end of the clip having the retuse portion 2| "extending to the'diametrically opposite side of the rod, and thus each tending to balance the other and eliminating or at least satisfactorily minimizing vibration of the rod or mandrel during rotation. To further enhance this effect when the cable itself is humped over the clip 2|,

the opposite end having reentrant portion I6 is made somewhat longer, measuring from the center of the inner spring loop l1, than the end over which the cable is humped, thus equalizing the forces referred to.

It will now be understood that the rod Ii] with the cable thereon as shown in Figure 1 may next be placed in an oven for curing or otherwise subjected toa vulcanizing temperature to cause the rubber or rubber-like sheath of the cable II to become resilient and to set the coils of the cable in helical form so that when extended, as when used for an extension cord, these will so automatically retract by their own resilience to closely compact helical form when released, thus minimizing the space occupied by the cord and avoiding entanglement 'withother objects.

' As will be understood, after such curing, the preliminary interconnected cable lengths 2'! re severed adjacent the apex of the hump 24, and also the leading end'portion 28 of the cable and the trailing end 29 are cut off adjacent the apex of each ofthe humps 22 and 25, respectively. This leaves each of the individualcable lengths 2'! desirably with a'connecting tail or tangent 3U at'ea'ch end.

' As shown in Figure 5, the arms IQ of the open inner spring loop I! of the clip [2 may be provided with a friction surface, for enhanced gripping action, as for example by being provided with sleeves I; of rubber or rubber-like material. As an alternative the mandrel could carry the friction creating material.

The spring clip l2 may be used advantageously to clip the leading end or trailing end of the cable to the rod even though the tangent ends for the cable be not'desired, in which case the hump formations of the cable may be omitted.

It is to be understood that the invention is not intended to be limited to details of construction shown for purposes of exemplification, and such changes may be made asfall within the scope of the appended claims without departing from the invention.

The invention having been described, what is here claimed is: I I

1. Means for making elastic coil cables comprising a vulcanizable material and embodying a mandrel, a spring clip device clipped to the mandrel by movement transverse thereto and bentto form an outer closed elongated loop having two, endsfone end of the device havin a re-entrant' portion directed inwardly and then slightly enlarged at its inner end to provide an open inner spring loop adjacent the center oi the device to grip'the mandrel, said mner spring loop, havin a continuation formed into a coil to provide a torsion spring and the other end of the device being formed to receive the cable thereon spaced from the mandrel and said torsion spring, thejreeentrant portion of the dc.- vice bein longer than the remaining portion of the device for balancing eifect when a portion of the cable is carried thereon and the mandrel is rotated to coil another portion of the cable thereon, said clip being adapted. to hold the portion of the cable thereon, substantially fixedly with respect to the mandrel during vulcanization of said material.

2. Means for making elastic coil cables com.-

prising a vulcanizable material, embodying a rotatable mandrel for coiling the cable, a member engageable with the mandrel by movement transverse thereto and having substantial portions extending transversely and on opposite sides of the axis of said mandrel, said member being provided with means for selectively and releasably securing said member to said mandrel and for holdin a portion of said cable transversely of the mandrel spaced from the mandrel during vulcanization of the material, that portion of the member extending to the side of the mandrel opposite the side at which the cable is held being the heavier of said member portions, whereby to provide a balancing efiect when a portion of the cable is carried on the member and the mandrel is rotated.

3. Means for making elastic coil cables comprising a vulcanizable material, embodying a rotatable mandrel for coiling a spring clip member engageable with the mandrel by movement transverse thereto and having substantial portions extending transversely and on opposite sides of the axis of said mandrel, said member being provided with a central open loop portion for grippingly passing a porthe cable thereon, 20

tion of the mandrel and an end portion of the cable therethrough to hold said portion of said cable in contact with the mandrel during rotation of the mandrel and vulcanization of the said material, the cable being held between the mandrel and bight of said loop portion, that portion of the member extending to the side of the mandrel opposite the side at which the cable is held being the heavier of said member portions, whereby to provide a balancing efiect when the mandrel is rotated.

RALPH J. ARNOLD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 458,115 Thomson Aug. 18, 1891 611,156 Trapp et al Sept. 20, 1898 1,533,367 Baylis Apr. 14, 1925 2,039,475 Campbell May 5, 1936 2,271,057 Barrans Jan. 27, 1942 2,339,683 Cox Jan. 18, 1944 

